Presynaptic Congenital Myasthenic Syndromes (PCMS) are a group of rare genetic disorders that affect the neuromuscular junction, leading to impaired communication between nerves and muscles. These syndromes are characterized by a decrease in the release of acetylcholine, a neurotransmitter responsible for transmitting signals from nerve cells to muscle cells.
In PCMS, mutations occur in genes that are involved in the assembly, function, and release of neurotransmitters at the presynaptic terminal of the neuromuscular junction. As a result, the amount of acetylcholine released is reduced, leading to weakness and fatigue in the affected muscles. The severity of PCMS can vary widely, ranging from mild weakness in early childhood to severe muscle weakness and respiratory distress in infancy.
Common symptoms of PCMS may include muscle weakness, easy fatigability, and delays in motor milestones development. These symptoms often worsen with exertion and can improve with rest. Additional features may include facial weakness, joint contractures, and feeding difficulties. PCMS can also present with various associated symptoms such as ptosis (droopy eyelids), ophthalmoplegia (abnormal eye movements), and scoliosis (curvature of the spine).
The diagnosis of PCMS typically involves a comprehensive evaluation of clinical symptoms, electromyography, and genetic testing. Treatment options for PCMS aim to improve neuromuscular communication and may include acetylcholinesterase inhibitors, which increase the availability of acetylcholine at the neuromuscular junction. Physical therapy and respiratory support may also be beneficial in managing symptoms and improving quality of life.
Due to the rarity and complexity of PCMS, individuals affected by this condition often require multidisciplinary care involving neurologists, genetic
